Class 9 Physical Security and DRM CIS 755: Advanced Computer Security Spring 2014 Eugene Vasserman
Administrative stuff Project proposal due today (2 pages) Quiz II and Exam I pushed back slightly – Quiz II next week
News! static OSStatus SSLVerifySignedServerKeyExchange(SSLContext *ctx, bool isRsa, SSLBuffer signedParams, uint8_t *signature, UInt16 signatureLen) { OSStatus err;... if ((err = SSLHashSHA1.update(&hashCtx, &serverRandom)) != 0) goto fail; if ((err = SSLHashSHA1.update(&hashCtx, &signedParams)) != 0) goto fail; if ((err = SSLHashSHA1.final(&hashCtx, &hashOut)) != 0) goto fail;... fail: SSLFreeBuffer(&signedHashes); SSLFreeBuffer(&hashCtx); return err; }
Trusted computing base (TCB) Software-level TCB Hardware-enforced software constraints Hardware-level TCB TPM:
Physical security Why use physical security? – Do Kerckhoffs’ principle or Shannon’s maxim apply? Tamper evidence Tamper resistance Properties? Differences? Assumptions? Trade-offs? Real-world examples
Blu-Ray DRM References “Broadcast encryption” An Overview of the Advanced Access Content System (AACS). Henry, Sui, and Zhong. Technical report, Revocation and Tracing Schemes for Stateless Receivers. Naor, Naor, and Lotspeich. Crypto,
Decryption Figure from the Overview tech report
Efficient keying and revocation Figures from the Overview tech report
Questions? Reading discussion